Sample Problems Distillation

SAMPLE PROBLEMS: Distillation- Over-all  Taken From: Miscellaneous Problems as Compiled, (some came from the Internet and others, from Quiz)

1. A mixture of 100 kgmol containing 78% benzene and 22% toluene is distilled by differential distillation until all the remaining liquid is 58.1% benzene. Determine (a) the amount of liquid left in the still (b) the composition and amount of distillate produced. Equilibrium Data Temperature (°C) 80.1 85.0 90.0 95.0 100.0 105.0 110.6

x 1.0 0.780 0.581 0.411 0.258 0.130 0.0

y 1.0 0.900 0.777 0.632 0.456 0.261 0.0

2. A mixture of 100 kgmol containing 78% benzene and 22% toluene is distilled by equilibrium/ flash distillation, and 50 kgmol was distilled and collected as distillate. Determine (a) the composition of the distillate (b) the composition and amount of the liquid produced (c) the temperature at which the distillation was carried. Graphs are available in calculations.

3. One hundred moles per hour of solution containing 80 moles of A, the rest is subjected to a simple continuous distillation. D moles of distillate containing 72 moles A is obtained. If A is five times more volatile than B, what is the concentration of A in the distillate?

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4. A 50% by weight benzene-toluene mixture is fed to a column at 180 F and 1 atm. What is the condition of the feed? (saturated liquid, saturated vapour, subcooled liquid or mixture of vapor and liquid).

5. A 537 kg solution of 50% by weight heptane and 50% by weight octane is batchdistilled until only 4.74 lbmol remain in the still. If the relative volatility is 2.0, what is the composition of the final liquid mixture?